Manhole covers with attachment means for decorative strips

ABSTRACT

An access cover for a manhole of the kind in which the removable cover member fits within an outer surrounding frame (2), the cover being in the form of an inner frame (5) containing an appropriate filling material (11), such as concrete. The appearance of the upper edges of the inner and outer frames is enhanced by providing the upper edges with decorative strips (12) which are positively fixed to the upper edges of the frame members (2, 6) by a tongue and groove joint (21, 22). Preferably, the groove (21) is formed with at least one splayed-out wall (20) which, after assembly, is pressed into longitudinal engagement with a corresponding wall of the tongue (22). An insulating layer (23) can be provided to prevent any chemical reaction between the frames and strips when they are of dissimilar metals.

This invention relates to access covers for manholes of the kind inwhich a removable cover member fits within an outer frame, the covermember also being fabricated as a frame (hereinafter referred to as aninner frame) which is filled with concrete or other appropriatematerial. An access cover of this kind is described and claimed in myU.K. Patent Specification No. 2,145,138.

In said Patent Specification the outer and inner frames are fabricatedfrom frame members which are cut to length to suit the opening to becovered. It will be appreciated that, once in position, only the upperedges of the frame members of the inner and outer frames are visible.The inner and outer frames described in my said Patent Specification arepreferably of aluminium, which enables the frame members to be formed asan extrusion suitably cut to length. However, it may be that theappearance of the upper edges provided by the frame members does notblend in with the surroundings, or suit the aesthetic requirements ofthe designer.

An object of this invention is to provide an arrangement in which theseupper edges can be readily provided to suit the intended surroundings.

According to this invention, an access cover for manholes of the kinddiscussed above is characterised in that the upper edges of the framemembers are shaped to provide a keying surface to which decorativestrips having a mating surface are affixed, said keying and matingsurfaces providing at least one co-operating tongue and groove.

Preferably, the cooperating tongue and groove is generally of dovetailform in cross-section, i.e. the corresponding side walk at least on oneside of the tongue and groove are inclined, or shaped, to provide apositive fixing against being pulled apart.

In some applications, particularly where two disimilar materials areused for the frame members and decorative strips, a chemical reactionmay be expected, e.g. galvanic corrosion between frame members ofaluminium alloys and strips of copper alloys, an interposing protectiveinsulating layer may be provided.

Where the frame members and strips are fixed together via a dovetailtongue and groove, preferably one of the side walls defining the grooveis splayed outwardly during forming so that, during assembly, thecooperating tongue and groove can be readily fitted together and theside wall thereafter crimped inwardly into longitudinal engagement withthe corresponding side wall of the tongue to provide said positivefixing.

In order that the invention may be readily understood, three embodimentswill now be described with reference to the accompanying drawings, inwhich:

FIG. 1 is a section through a prior art access cover and outer framegenerally as described in my said Patent Specification, and

FIGS. 2 to 4 respectively are enlarged modified views of upper edges 1,5 of FIG. 1 illustrating three embodiments of the present invention.

Referring to FIG. 1, the access cover is preferably rectangular in planand has an outer frame 2 comprising four a L-shaped frame member, whichis located over a wall 3 partially defining an opening and fixed inposition by concrete 4 via keying flanges 4a formed along the rear facesof the frame members. The inner frame 5 is similarly formed from anL-shaped frame member 6 which are a snug fit within the outer framemembers, particularly around the upper edges thereof where the framesare sealed together by a sealing strip 7. The horizontal limbs of theinner frame members 6 each have a grooved lower surface 8 which sits onthe upper surface 9 of the respective horizontal limb of the outer framemembers 2. The inner frame members 6 also have keying flanges 10 intheir rear faces to fix the concrete filling material 11 within theframe.

In accordance with this invention the upper edge of the frame members 2,6 comprise decorative strips 12 (see FIGS. 2 to 4) applied thereto,according to requirements. These strips are joined to the frame membersapproximately along the line X--X and may either be of metal, e.g. acopper alloy, or of a suitable plastics material of an appropriatecolour.

Referring to FIGS. 2 to 4, the embodiments described are in respect offrame members 2, 6 of aluminium and decorative strips 12 of brass.

Referring to FIG. 2, in the first embodiment, the frame members andstrips each have a symmetrical dovetail groove 15, 16 formed therein andan interposing layer 17 is provided as a reinforced plastics extrusionwith co-operating dovetail shaped tongues 18, 19 projecting from each ofits faces. The components may be fixed by forming the decorative strip12 and frame member with a respective splayed-out side wall 20, 20awhich can be crimped against the corresponding side wall of theco-operating dovetail tongue. In this way other fixing means, such as anadhesive is not required for positive fixing. If preferred, the stripand the frame member can each be formed with both side wallssplayed-out, which are then crimped from respective sides intoengagement with their respective tongues.

Referring to FIG. 3, in the second embodiment, a symmetrical dovetailgroove 21 is formed in the strip 12 and a co-operating tongue 22 in theframe member and the two metals are separated from each other by asuitably shaped plastics extrusion 23, or insulating tape. As in thefirst embodiment, the components may be fixed together by crimping.However, it will be appreciated that only the strip 12 would be providedwith a splayed-out side wall, or walls.

Referring to FIG. 4, in the third embodiment, an assymmetrical dovetailjoint is provided, having differently shaped side walls, the groovebeing formed in the frame member and cooperating tongue 24 in thedecorative strip 12. This arrangement facilitates interposing theinsulation layer 26, which in this case is insulating tape, by adheringone side of the tape onto and around the tongue 24 before it is fittedinto the groove, which has only one shaped, splayed-out wall 25, whichis shaped to mate with the shape of its corresponding tongue side wall.

It will be appreciated that, in a production line, the frame members anddecorative strips would be formed by joining extruded lengths of framemember and strip section together and then cutting them to lengthsappropriate to the dimensions required for the outer and inner frames.Where the section(s) have splayed-out walls, crimping would be effectedby traversing along the length of each splayed-out wall with a pressureroller or rollers to move the wall into longitudinal contact with itscorresponding tongue side wall.

I claim:
 1. An access cover for manholes in which a removable covermember fits within an outer frame, the cover member being fabricated asan inner frame which is filled with concrete or other appropriatematerial,wherein at least one upper edge of the inner and outer framemembers is shaped to provide a keying surface to which a decorativestrip having a mating surface is affixed, said keying and matingsurfaces provide at least one cooperating tongue and groove, the grooveis defined by two side walls and is of a dovetail form in cross-section,and one of the side walls is malleably deformable whereby said one sidewall is formed splayed-outwardly to facilitate assembly of thecooperating tongue with the groove and whereby said one side wall maythereafter be crimped inwardly into longitudinal engagement with thecorresponding side wall of the tongue to provide a positive fixing ofthe tongue with its corresponding groove.
 2. An access cover accordingto claim 1, wherein the tongue and the groove are symmetrical incross-section, and the groove is provided on the decorative strip andthe tongue is provided on one of the frame members.
 3. An access coveraccording to claim 1, wherein the tongue and the grove are asymmetricalin cross-section, and the two side walls defining the groove are ofdifferent shape.
 4. An access cover according to claim 3, wherein thetongue is formed on the decorative strip.
 5. An access cover as claimedin claim 1, wherein a protective insulating layer is provided betweenthe upper edge of one of the frame members and the decorative strip toprevent any chemical reaction between the decorative strip and the framemember.
 6. An access cover as claimed in claim 5, wherein the insulatinglayer is in the form of a tape which is adhered on one side onto andaround the tongue before the tongue is fitted into its cooperatinggroove.
 7. An access cover for manholes in which a removable covermember fits within an outer frame, the cover member being fabricated asan inner frame and filled with concrete or other appropriatematerial,wherein upper edges of both the inner and outer frame membersare shaped to provide keying surfaces to which decorative strips havingmating surfaces are affixed, each of said keying and mating surfacesprovides at least one cooperating tongue and groove, each groove isdefined by two side walls and is of a dovetail form in cross-section,and one of the side walls of each groove is malleably deformable wherebyeach said one side wall is formed splayed-outwardly to facilitateassembly of each said cooperating tongue with its associated groove andwhereby each said one side wall may thereafter be crimped inwardly intolongitudinal engagement with its associated tongue to provide a positivefixing of each tongue with its corresponding groove.